A cashback bonus is a type of promotion given to online casino players for their losses of particular amounts of real money. It is usually a percentage of what the players lost during a certain period at a casino's cashier. For example, if a player was to lose $100 playing roulette, they may receive a cashback bonus of 10% of their losses, which is $10. Cashback bonuses are a great way for players to get some of their money back, even after having lost.